1. Favors certain types of businesses that can more readily arbitrage their domicile (e.g. Apple, Google).
2. Creates an incentive for companies to pay accountants and lawyers a large amount of money to find ways to engage in #1. All of this money is, in economic terms, deadweight loss.
If you look at the effective tax rates companies were paying before this change, they were more or less harmonized with the rest of the world[1]. What was not harmonized was the statutory rate. What this meant in practice is that big companies with the resources to exploit the loophole paid the low rates, and companies without those resources paid the high rates. And the resources that were expended by the companies to accomplish this were 100% unproductive. Harmonizing the statutory rate makes things fair, and eliminates the need to waste money on those types of accountants.
I would argue that is not an issue because that happens anyway. There is not, nor will there ever be a tax point where these huge companies don't attempt to get out of paying taxes.
However, like everything else in our country -- what's superficially a good idea gets cut to pieces by private interests and it ends up benefiting them.
In a perfect world a corporate tax cut would be offset by hefty consumption taxes for the rich, and estate taxes. But that of course did not happen, and will not happen in a republican-controlled government.
The point of the tax cut was to get more money in the hands of owners of corporations. And, so far, it's working quite well. We won't see much wage growth for one big reason, the Fed has and will continue to raise interest rates at the slightest sign of inflation.